Circuits for electron discharge devices



March 12', 1935. M. MASNOU 1,994319 CIRCUITS FOR ELECTRON DISCHARGE DEVICES Filed 00:0. 29, 1924 2 Sheets-Sheet 1 A? Inn-"mill lnVentor:

Maw-ice Masnou T H is Att'ovn ey.

March 12, 1935. M. MASNOU 1,994,319

CIRCUITS FOR ELECTRON DISCHARGE DEVICES Filed Oct. 29, 1924 2 Sheets-Sheet 2 M&ur-ice Mas cu,

y W H is AUcovn ey.

Patented Mar. 12, 1935 UNITE s'rarss "'1 ,994,s 9 V crnourrs Foe ELECTRON DISCHARGE A DEVICES Maurice Masnou, Paris, France, assignor to General Electric Company, a corporation of New York ApplicationOctober 29, 1924, SerialINo. 746,561

In France November 3, 1923 Claims. (01. 17-95-171) My present invention relates tocircuit arrangements for use with electron discharge devices, particularly thermionic tubes of the three-electrode type. '5 It is well known that the plate current of a three-electrode thermionic tube is affected by variations in the current supplied for heating the usual filamentary cathode, for example, a telephone inserted in the plate circuit will give a 10 sound whose pitch is a ftmction of frequency of variations of the heating current. If a resistance is placed in shunt to the filament terminals and the plate'circuit is brought to a point in this resistance havingthe same potential as the central 5 point of the filarn'entthe noise in the telephone will decrease inintensityr If the grid potential is made negative the noise will be still further decreased, but when several tubes are coupled together by transformers or resistance'couplings, the noise produced inthe output circuit of the last tube will still be very objectionable.

The object of my invention is to provide circuit arrangements whereby the cathodes of three-electrode thermionic tubes may be supplied with ya.-

riable heating current, such, for example, as a low frequency alternating current, and the effect of the variations in the heating current upon the output circuit ofthe last tube of a series will be eliminated to such an extent that it will be unobjectionable. The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, my invention itself, howeven'both as to its organization and method of operation will best be understood by reference to the following description taken in'connection with the accompanying drawings in which Fig. 1 shows diagrammatically a circuit arrangement in which my invention is applied to a system for amplifying radio frequency currents; Fig. 2 shows the application of my invention to the detection of highfrequency currents; Fig. 3 shows its application tothe amplification of audio frequency currents; and Fig. 4 shows a circuit arrangement in which all three of the functions of Figs. 1,2

and 3 are combined in one, circuit organization.

' In the arrangement of Fig. 1', Ihave indicated two tubes 1 and 2, the cathodes of which are heated by means of alternating currents supplied by the transformers 3 and e. The grid and plate returns are brought to intermediate points in the resistances 5 and 6, which are shunted across the transformersecondaries. The plate circuit of device 1 includes the usual battery 7, resistance 3 and primary 9 of the transformer 10. The resistance. 8 is connected in series with the secondary ll of transformer lo'and in the grid circuit of device 2. The plate circuit of tube 2 includes a battery 12 and primary 13 of an output transformer; The signals to be amplified are impressed -5 upon-the grid circuit of tube 1 by means of an input transformer 14; .Thegrid'of tube 1 is preferably made negative by. means of a biasing battery 15. When the heating currents of the two tubes increaseithe plate currentstend to increase. 10

An increase inplate current in tube 1 tends to make the gridof tube 2 more negativeandthis counteracts the tendency of the plate current of tube 2. to increase. The primary and secondary windingsi) and 11 of transformer 10 are con- 15 nected in such a waythat the signaling potentials impressed upon the grid of tube 2 through the transformer reinforce the signal potential impressed uponrthe grid of tube 2 by means of re? sistance 8. II have found that. with the arrange- 20 mentdescribed amplified radio frequency current supplied to theoutput of transformer 13 isv as free from fluctuations due to the heating current as would be the case if the cathodes of the tubes had been heated by direct current.

In the arrangement shown in Fig. 2, tube 1 is made to serve as a detector byinserting the usual grid condenser 16 and grid leak 17 in the gridcircuit; In this casethe grid oftube 1 is preferablytmade'positive by means of the biasing 0 battery l8.- The platecircuit of tube 1' includes the primary winding 19 of an audio frequency transformerand a choke 20, whose impedance is substantially negligible for currents of the frequency employed for heating the cathodes. The 35 voltage variations at the terminals of; choke 20 are-supplied to the grid of tube 2 through a condenser 21. A discharge resistance 22 in the grid circuit to tube 2 insures a suitable mean poten tial forthe grid of that device. A resistance 23 is 40 also preferably included in the plate "circuit of tube 2, although this may be omitted if desired.

It will be observed that with the connections shown the plate currents of tubes; 1 and 2 flow in opposite directions'throughthe primary 19 of 4 the audio frequency transformer 24.

.The operation of this system is as follows:

The circuits are so adjusted that when no signals are being received the plate current variations in the two tubes are equal, and since the 5 two currentsflow in: opposite directions through the primary 19 of transformer 24 no effect will be produced in the output circuit. When, however, a signal is received a potential variation is produced acrossthe choke 20, which is applied 55 through the condenser 21 to the tube 2. This causes the current through tube 2 to vary in the opposite direction to the variation of current in tube 1, and. thus the changes in the signaling currents of the two tubes flowing through primary 19 of the audio frequency transformer 24 reinforce each other.

In the arrangement shown in Fig. 3, which is adapted for the amplification of audio frequency currents, the telephone receiver 25 is inserted in the two plate circuits in such a way. that the two plate currents flow through the telephone receiver in opposite directions. The action of the circuit in eliminating the effect of variations in the heating current and the reinforcing of the signaling currents produced in the two plate circuits are similar in this case to that occurring in Fig. 2. The grid of the device is in this case preferably made negative by the biasing battery 26. If desired, a resistance may be inserted in the plate circuit of device 2, as in the arrangement of Fig. 2, and the telephone receiver 25 may be connected to the plate circuits by means of a transformer.'

In the arrangement. of Fig. 4 I have shown a six-tube outfit adapted for the amplification and detection of radio signals received upon an. an-

tenna 27. .Heating current for thefilament of a all of the tubes maybe supplied by transformer 28, having a single-primary winding29 and individual secondary windings 30 to inclusive. If desired, independent transformers may be used. A transformer having considerable leakage flux is also advantageous. Tubes 36 and 37 act as radio amplifiers and are connected by means of the high frequency transformer 38 to the grid circuit of the tube 39, which acts as a detector. Tube 39 in conjunction with tube 40 also serves as an audio frequency amplifier as in the arrangement shown in Fig. 12, andtubes 41 and 42 act as a low frequency amplifier in the manner described in connection with Fig. 3. Batteries 43, 44 serve to supply plate currents to the three pairs of tubes. M

It will of course be understood that the circuit arrangements described may equally well be used where the plate circuits of the tubes are supplied by suitably rectified alternating current,

While I have shownand described certain ap plications of my invention, it will be obvious that many modifications in the manner in which it is applied may be made without departing from the scope thereof as set forth in the appended claims. 7

What I claim as new and desire to secure by Letters Patent of the United States is:-

1'. A circuit arrangement for three-electrode thermionic tubes comprising a pair of cascade connected tubes having plate and grid circuits, means for supplying variable currents for heating the cathodes of said tubes, and means common to a circuit of each tube whereby variations in the plate current of one tube produced by reason of variations in the heating current'are compensated by the variations in the plate current of the other tube. V

2. A circuit arrangement for three-electrode thermionic tubes comprising a pair of tubes having plate and grid circuits, means for supplying variable currents for heating the cathodes of said tubes, said tubes being connected incascade for successive amplification, means common to a circuit of each tube whereby variations in the plate current of onertube produced by variations the heatingcurrent are compensated by the 3. A circuit arrangement for three-electrode 5 thermionic tubes comprising a pair of cascade connected tubes having plateiand grid circuits, means. for supplying low frequency alternating currents for heating the cathodes of said tubes;

means common to a plate circuit ofeach'tube 10 whereby. variations in the plate current of one tube produced by'reason .of variations in the I; V

heating current are compensated bythe varia tions in the plate current of theother tubc'and high frequency coupling means connected in cir- 15, cuit with said last means whereby high frequency variations are supplied from one tube tothe other.

4. A circuit arrangement for three-electrode V thermionic tubes comprising a pair of tubes hav- 20 ing plate and grid circuits, means forsupplying low frequency alternating currents for heating the cathodes of said tubes, said tubes being connected in cascade for successive amplification,

means common to the plate circuit of one tube and .the grid circuit of the other. .tube whereby variations in the platecurrent of.one tube proe duced by variations in the-heating current are compensated by thevariations in the plate cur-' rent of the other tube, additionalv means 'cone 30 nected in circuit with said last means whereby variations in a signaling current in onetube pror duce amplified variationsin signaling currentin the other tube.

. 5. A circuit arrangement for three-electrode 35 7 thermionic tubes comprising a pair of tubes ha'ving plate and gridcircuitameans for supplying variable currents for heating the cathodesof said tubes, means forsupplying signaling currents to the grid circuit of one tube, means for 4Q supplying amplified current variations from the plate circuit of the first tube to the grid circuit of the second tube, and a conductive connection from the plate circuit of the first'tube to the grid circuit of. the second tube for compensating 5. the efiect in the plate circuits of the twotubes' v of variations 'in the plate current produced by reason of variations in'the heating currents.

6. A circuit arrangement for three-electrode thermionic tubes comprising a pair of tubes have 5.0 ing plate and grid circuits, means for supplying Of'said' tubes, means'for supplying signaling currents-to, 7

variable currents for heating the cathodes the grid circuit of one tube, means for supplying j amplified current variations from the plate circuit e5 of the first tube to the grid circuitof the second I tube, and a conductiveconnection between the" circuits of the two tubes for compensatingthe I v effect in the plate circuitof the second tube of variations in the plate current produced by rea fill son of variations in the heating currents.

7. The method of reducing disturbing effects of i variable energizing currentsin the circuits ofia cascade system of electron discharge devices,

which includes applying the disturbing currents arising in a circuit of each alternate discharge device in the cascade system to a circuit of the next 1 adjacent discharge device intermediate said alter nate discharge devices in phase to neutralize the disturbing current arising in the respective next adjacent discharge device.

8. A circuit arrangement for three-electrode thermionic tubes comprising'a pair oftubes having plate and grid circuits, means for supplying variable currents for heating the cathodes of said 15 I r tubes, said tubes being connected in cascade for successive amplification, means common to a circuit of each tube whereby variations in the plate 9. A circuit arrangement for three-electrode thermionic tubes comprising a plurality of tubes having plate and grid circuits, means for supplying variable currents for heating the cathodes of said tubes, said tubes being connected in cascade.

for successive amplification, and connections whereby variations in the plate current of one tube produced by variations in the heating cur-.

rent act on the grid of the next adjacent tube in said cascade arrangement to prevent variations in the plate current in next adjacent tube.

10. A circuit arrangement for three-electrode thermionic tubes comprising a pair of tubes having plate and grid circuits, means for supplying variable currents for heating the cathodes of said tubes, said tubes being connected in said cascade for successive amplification, and an impedance connected in the plate circuit of one tube and in the grid circuit of the other tube whereby variations in the plate circuit of one tube resulting from heating current variations in said tube and variations in the heating current of the other tube produce compensating effects on the plate current of the other tube.

MAURICE MASNOU; 

